/**
 * 
 */
package acmCoder.ctrip;

import java.util.HashSet;
import java.util.Scanner;

/**
 * @author zhongfang
 *
 */
public class test1 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		String string = scanner.nextLine();
		scanner.close();
		HashSet<Character> characters = new HashSet<>();
		StringBuilder sBuilder = new StringBuilder();
		for (int i = 0; i < string.length(); i++) {
			if (characters.add(string.charAt(i))) {
				sBuilder.append(string.charAt(i));
			}
		}
		System.out.println(sBuilder);
	}

}
